JOHANNESBURG, AUG. 24 -- The South African government, responding to a wave of black tribal violence that has left more than 500 people dead in 12 days, declared a limited state of emergency today in 17 districts around Johannesburg where the worst violence has occurred.

Law and Order Minister Adriaan Vlok also announced a strict prohibition on carrying dangerous weapons and said police strength in the trouble areas would be "drastically increased" to control the violence.

The crackdown measures, foreshadowed by President Frederik W. de Klerk in a speech Thursday, drew sharp criticism from the African National Congress.

Nelson Mandela, the ANC deputy president, who met with de Klerk today, said they would be "totally useless" in stemming the violence, and he protested that his black nationalist organization had not been consulted before the proclamation was issued.

"The ANC objects to the principle of the government acting unilaterally on the question of resolving violence," Mandela said.

Despite its critical reaction, there was no indication that the ANC would take any action that might derail the delicately poised negotiations between it and the white minority government, aimed at paving the way to eventual abolition of apartheid and extension of a share of political power to the nation's black majority.

The government's announcement today came amid signs that the wave of violence was subsiding. For the second successive day, there was relative quiet in the chain of townships stretching along the Witwatersrand to the east and west of Johannesburg, apart from a few sporadic clashes between supporters of Zulu Chief Mangosuthu Buthelezi's Inkatha Movement and the ANC.

Government spokesmen, seemingly anxious to cushion international reaction, were at pains to emphasize that the special powers invoked by Vlok did not amount to a reimposition of the three-year state of emergency that de Klerk had lifted June 8.

They noted that the new proclamation was issued under a different law allowing for particular areas to be declared "unrest areas" and for special restrictions to be imposed in them.

However, the new restrictions, which were published soon after Vlok made his announcement, are almost identical to the former emergency regulations.

Political protest meetings, marches and gatherings are prohibited, as they were under the state of emergency, and the police are empowered to detain people without charges for repeatable periods of 30 days.

Anyone may be searched without a warrant, and, as during the emergency, the police are indemnified against any legal actions for damages.

Vlok said the new proclamation was effective for only three months, compared to a year for the state of emergency. However, the published regulations made clear that the minister can renew the proclamation as often as he wishes.

Government spokesmen have stressed, too, that the new proclamation does not restrict the media, which were severely limited during the emergency. But the regulations empower any police officer to order any person to leave an "unrest area" -- a provision reporters say can be used to keep them from covering news in the same way as was done under the state of emergency.

The ANC has repeatedly charged that the police have played a partisan role in the violence, siding with Inkatha fighters to promote tribal strife and destabilize the negotiating process.

Mandela said that in earlier talks with the government, the ANC had proposed a simpler and more effective way of ending the violence than the government's measures. This was for the police to monitor migrant workers' hostels, which have been the main sources of the violence in the black townships, and prevent armed men from leaving them to attack township residents.

At the same time, the police should prevent township residents from harassing hostel dwellers, Mandela said.

The ANC contends that the violence began in the hostels when Zulu migrant workers who support Inkatha began an enforced recruitment drive, then spread as the Zulus launched attacks on the surrounding community, resulting in a cycle of reprisal raids.

One aspect of the government's new restrictions that has met with general approval is the ban on carrying dangerous weapons.

Throughout the violence, reporters saw Zulu warrior units leave migrant hostels carrying axes, butcher knives, spears, machetes, sharpened iron rods and home-made shotguns with barrels cut from iron piping.

Police have not disarmed them, saying it is part of Zulu "cultural tradition" to carry weapons and that the law allows this.

This has led to ANC supporters arming themselves as well, mostly with gasoline bombs and occasionally Soviet-made AK-47 automatic rifles, with which the organization's military wing has been equipped.